I'm pretty sure this is the book I was thinking of: https://www.abebooks.com/9780870001598/Myths-Antitrust-Economic-Theory-Legal-0870001590/plp

In the case of a highly regulated and protected industry like healthcare, it doesn't surprise me at all that this sort of thing happens. My wife worked in hospital admin, briefly, so I have a little bit of exposure, in addition to the many episodes of Econ Talk on the subject. There are so many barriers to entry for competitors, but they're all artificial creations of the state.

I don't think these kinds of exercises of market power are feasible, more generally.